In vivo imaging methods to assess glaucomatous optic neuropathy

Abstract

The goal of this review is to summarize the most common imaging methods currently applied for in vivo assessment of ocular structure in animal models of experimental glaucoma with an emphasis on translational relevance to clinical studies of the human disease. The most common techniques in current use include optical coherence tomography and scanning laser ophthalmoscopy. In reviewing the application of these and other imaging modalities to study glaucomatous optic neuropathy, this article is organized into three major sections: 1) imaging the optic nerve head, 2) imaging the retinal nerve fiber layer and 3) imaging retinal ganglion cell soma and dendrites. The article concludes with a brief section on possible future directions.

Assessment of retinal ganglion cell damage in glaucomatous optic neuropathy: Axon transport, injury and soma loss

“…The primary advantage of these strains is the selective identification of RGCs without the need for invasive procedures to introduce a retrograde tracer. These strains are particularly useful for longitudinal in vivo imaging studies (reviewed by Fortune, 2015; in this special issue). The remainder of this section focuses on characterization and use of Table 3 Rat RGC quantification studies in the absence and presence of optic nerve injury.…”

“…Assessing axonal transport and degeneration along with assessing morphologic and functional changes to RGCs, and ultimately their loss, in experimental models is essential for improving our understanding GON pathophysiology. The aim of this review is to highlight the most commonly used techniques to assess and quantify RGC damage ex vivo in experimental models of GON (for an in depth discussion on in vivo techniques, refer to Fortune, 2015; in this special issue). While these techniques are extensively described in the literature for various applications and combinations, here we present an overview and objective discussion of each method to allow researchers to determine the most appropriate tools for their studies.…”

Comparing Optic Nerve Head Rim Width, Rim Area, and Peripapillary Retinal Nerve Fiber Layer Thickness to Axon Count in Experimental Glaucoma

“…Imaging techniques, such as optical coherence tomography (OCT), serve as an important aid in the diagnosis and management of glaucoma principally because they enable reliable, quantitative assessment of optic nerve head (ONH) and retinal nerve fiber layer (RNFL) structural integrity. 1 – 4 In this regard, OCT and other imaging techniques may help the clinician to detect the characteristic deformation of ONH connective tissue structures as well as the progressive degeneration of retinal ganglion cells and their axons, the primary cause of vision loss in glaucoma.…”

Whole-globe biomechanics using high-field MRI

“…Currently, there are few methods for non-invasively measuring tissue deformation over the whole globe, which include ultrasound, optical coherence tomography (OCT), and computed tomography (CT), but they all have important limitations (Bajwa et al, 2015; Brown et al, 2016; Fortune, 2015). Ultrasound has excellent penetration depth allowing for quantitative biomechanical analysis of the sclera and cornea, but insufficient resolution to discern the fine structures of the optic nerve head (ONH) (He and Liu, 2009; Palko et al, 2016).…”